Electric incandescent lamp



July 31, 1923. B. E.- SHACKELFORD ELECTRIC INCANDESCENT LAMP Filed Marsh 9, 1918 ATTORNEY Patents July 31, 1923.

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BENJAMIN E. SHACKELFORD, OF EAST ORANGE, NEW JERSEY, ASSIGNOR TO WEST- INGHOUSE LAMP COMPANY, A CORPORATION OF PENNSYLVANIA.

ELECTRIC INCANDESCENT LP.

Application filed march}, 1918. Serial No. 221,360.

To all whom it may concern:

Be it known that I, BENJAMIN E. SHACK- ELFORD, a citizen of the United States, and a resident of East Orange, in the county of Essex and State of New Jersey, have invented a new and useful Improvement in Electric Incandescent Lamps, of which the following is a specification. This invention relates ,to improvements in incandescent electric lamps, and more especially to that type of lamp used for signalling purposes. In signal lamps, and particularly those used for daylight signalling, the principal requirements of a satisfactory l lamp are, firstly; that it may be lighted and extinguished very rapidly so as to emanate a succession of distinct light flashes of sufficient beam candlepower or intensity as to be capable of being projected long distances, and

I secondly; that the lamp possess a useful life sufiiciently long so as to make it practical.

An object of the invention is the provision of a lamp, which, among other things, will be characterized by the features of being capable of rapid incandescence and extinction when responding to a series of current impulses, thus roducing in rapid succession, light flashes su tantially synchronized with the current impulses.

Another object is the provision of a lam having a high beam candlepower or big concentration so that when associated with an optical system, the light may be projected great distances. Other objects of the invention have to do with various features of construction, combinations and arrangements of parts, hereinafter set forth and defined by the appended claims.

In the accompanying drawing, Fig. 1 is a view of a lamp embodying the invention.

According to this invention there isv provided a lamp bulb, preferably spherical in shape, having a filamentt mounted therein of highl refractory material such as tungsten, an surrounded by an atmosphere of some gas having the property of high heat conductivity such as hydrogen. It is desirable that the filament be of the type known in the lamp art as a concentrated filament, and that it be mounted near the center of a spherically shaped lamp bulb. Itis also desirable that the gaseous fillin within the lamp bulb be of a substantia pressure at the operating temperatureof the l lamp, so as to retard the vaporization of the filament, and also increase the cooling efi'ect thereon.

Referrin more particularly to the drawmg the re erence character 1 designates a lamp bulb, within which is mounted a filament 2 of the concentrated type, supported by supports 3 composed of any metal commonly used for supports and of such size that it is comparatively rigid, the supports extending from a stem it into which they are sealed. The filament 2 is positioned about the center of the bulb and is draped or held in saw-tooth formation between the hook extensions of the supports '3. The ends of the filament are secured to heavy nickel lead-in wires 5 tipped with tungsten or molybdenum, serving to carry current to the filament and conductors 6. The lead-in conductors 5 pass through the usual glass seal 7. It would appear that by sup rting the filament 2 substantially centra ly of the bulb 1, a better circulation of the convection currents set up within the bulb is obtained, with a consequent improvement in the coolmg effect of the gaseous filling upon the filament.

Altho any gas having the property of high heat conductivity will serve as a gaseous filling for the bulb l, for reasons to be explained it is preferred to use hydrogen. It was previously considered harmful to have hydrogen in the bulb for as there were very apt to be decomposable oxides of some sort therein, these were reduced by the hydrogen when the filament was heated and resulted in the formation of water vapor which was very objectionable and attacked the filament. According to this invention, however, lamps of this type containinghydrogen, unmixed with other gases, have been produced which have operated successfully for the purpose desired. There is a relation between the gas pressure within the lamp and such other factors as the kind of filamentary material used, the cooling effect ex erted by the gas upon the filament, etc. It has been found by experiments that very satisfactory results are obtained when the pressure of the gas is, at the operating temperature of the lamp, substantially that of the atmosphere. The factors which determine the pressure of the gas are variable, and must be taken into consideration when lighting up of the filament and consequently higher heam candlepower.

The cooling edect of the hydrogen, due to its high conductivity of heat, efl'ectuates the rapid cooling of the filament when the cur-' rent is interrupted. The term conductivity as used herein, maybe defined to include hoth convection and conduction losses which are occasioned by the presencehf the hydrogen. What appears to actually take place when the filament is in an incandescent state, is a sudden heating ofthe gas immediately surrounding the filament, and since hydrogen is one of the light gases,,the molecules thereof are comparativel free to move, thus permitting the instant thrmation of strong convection currents which in turn have a cooling edect upon the filament. it is, there'- fore, really the combined conduction and convection losses which producethe sudden quenching of the filament upon the interruption or the current, and this is the meaning desired "to he imported wherever the to conductivity has heenused.

It, therefore, follows that the construction of a lamp as contemplated by this invention, permits of the lighting and extinguishing of the lamp in rapid'succession when res onding to a series of current impulses.

ests have proven that with such a lamp, when in a. circuit in series with an inter- I rupter, such as a telegraph lrey, distinct light flashes may be caused to be given from the lamp at the same speed at which such a key is usually operated. A lamp made in accordance with this invention, when associated with an optical system, such as a reflector and condensing lens, has given oil or produced light flashes which could he ohserved very distinctly by the naked eye on a clear day at a distance of ten miles or more, and of course, these flashes were visihle at a much greater'distance when viewed through a field glass or the like.-

While this invention has heen set forthand particularly described in a certainpreferred emhodiment, it will he understood that modifications might he made without departurefrom the spirit and scope thereof, and it is not wished that the invention he limited to the precise details of construction illustrated.

t l claim as my invention isi 1. An electric si al lamp comprising a hydrogen, at a'substantial pressure, a con centrated tungsten filament therein mounted near the center of the envelope, capahle of rapid incandescence and extinction when responding to a series of current impulses and thus adapted for producing in rapid succession, light flashes suhstantially syn chronized with current impulses.

2. An electric signal lamp comprising a I substantially s he-rical envelope filled with hydrogen at su tantially atmospheric pressure when in operation, a concentrated fila ment of tungsten therein mounted near the center of the envelope and adapted to he,

prising a hulh filled with hydro on at ahout' atmospheric pressure when the amp is operated and a tungsten filament oi the concentrated type therein, adapted for operation at a high temperature, the hydrogen serving to rapidly extinguish. the filament when the current therethrough is discontinued and retarding excessive evaporation therefrom.

l. A. high-speed electric signal lamp comprising a substantially spherical envelope containing hydrogen at suhstantially atmospheric pressure at the operating temperature of the lamp, a concentrated filament of tungsten therein mounted near the center ltlll of the envelope, the function of the hydrogen being to prevent evaporation of the filer ment and exert a rapid quenching etlect thereon when die-energized, whereby the lamp is capable or emitting distinct light flashes in rapid succession when responding to current impulses.

5. The method 7 of rapidly producing flashes of light comprising subjecting a concentrated filament of tungsten in an atmosphere of hydrogen at a substantial pressure to rapid current impulses. at over voltage.

-6. The method of producing a series of flashes'of light substantially synchronized with supplied energy comprising supplying a series of impulses of current at an excess voltage, thereby giving a shock excitation efiect, to a concentrated tsten filament in an atmosphere of hydrogen under a suhstantial prre.

7. The method of generating distinct flashes of light in rapid succession comprising subjecting a refractory metal ament in an atmosphere of h drogen to current imllll llli

pulses at such a vo tage as'tc produce the edect of a shoclr excitation, wherehy rapid incandeseence occurs in the filament fol= lowed h rapid extinction from the cooling 6c suhstantially spherical envelope ed with efiect o the hydrogen.

8. The method of rapidly signalling by rapidly incandesced when an impulse is 19 means of light flashes comprisiu energizing impressed and rapidly quenched by the hy-' a'concentrated refractory metal lament cendrogenafter the termination of the imtrally located in a substantially spherical pulse. t

5 bulb' containing hydrogen at substantially In testimony whereof, I have hereunto atmospheric pressure when the filament is subscribed my name this 13th day of Feb- 15 energized, by means of current impulses at ruary 1918. excessive voltage following each other in rapid succession, whereby the filament is I BENJAMIN SHACKELFORD. 

